The Princesses of Ruin by Ember Holt

An ancient prophecy demands its due.
A dark goddess rises to reclaim her throne.

With Ashai on the brink of tearing through the veil between realms, Scarlett, Lily, Alyse, and Reina unite the broken kingdom to send her back to the nine hells. But when a weapon designed to destroy her fails, Ashai encases herself in an impenetrable shield, barely escaping death.
Now, the princesses must embark on separate perilous journeys—battling monsters, subduing giants, and retrieving deadly ingredients for the ritual that could banish the dark goddess forever. As they face treacherous trials and strike dangerous bargains with cunning entities, the fate of the world hangs by a thread.
One misstep from the princesses could spell utter ruin for all.

Throne of Glass meets Six of Crows +smut in this pulse-pounding finale of the dark romantasy series where danger, desire, and destiny collide.